Dynamic Factor Demands for Aggregate Southeastern United States Agriculture

A four equation input demand system for aggregate Southeastern United States agriculture consistent with dynamic optimizing behavior is specified and estimated. Labor and materials are considered as variable inputs while land and capital are treated as quasi-fixed inputs. It is found that the adjustment rates for capital and land differ considerably and are interdependent. Further, the data appear consistent with the existence of an aggregate production technology and the hypothesized optimizing behavior.Farm Management,

Agricultural science policy

Technological advances developed through R&D have supplied the world with not only more food, but better food. This report looks at issues raised by this changing environment for agricultural productivity, agricultural R&D, and natural resource management.Agriculture and state ,

Effect of organic crop rotations on long-term development of the weed seedbank

Changes in the weed seedbank were monitored between 1991 and 1998 in two experiments that were established to compare organic crop rotations at two sites in NE Scotland. Two rotations, replicated twice at each site, were compared and all courses of both rotations were present every year. There were relatively minor changes in weed species diversity over time, but major changes in seedbank abundance. Weed seed numbers were relatively low in rotations with a high proportion of grass/clover ley. Differences in level of seedbank across the rotation were relatively predictable at Tulloch but much less so at Woodside where factors such as the effect of the grass/clover ley seemed to play a lesser role. Other factors, such as weather and its influence on the effectiveness of weed control operations, and higher populations of ground-living arthropods, may be affecting the Woodside seedbanks

Thermodynamic stability of ligand-protected metal nanoclusters

Despite the great advances in synthesis and structural determination of atomically precise, thiolate-protected metal nanoclusters, our understanding of the driving forces for their colloidal stabilization is very limited. Currently there is a lack of models able to describe the thermodynamic stability of these ‘magic-number’ colloidal nanoclusters as a function of their atomic-level structural characteristics. Herein, we introduce the thermodynamic stability theory, derived from first principles, which is able to address stability of thiolate-protected metal nanoclusters as a function of the number of metal core atoms and thiolates on the nanocluster shell. Surprisingly, we reveal a fine energy balance between the core cohesive energy and the shell-to-core binding energy that appears to drive nanocluster stabilization. Our theory applies to both charged and neutral systems and captures a large number of experimental observations. Importantly, it opens new avenues for accelerating the discovery of stable, atomically precise, colloidal metal nanoclusters

The measurement of attitudes toward abortion

Attitudes towards abortion have been a focal point within politics and religion for many years. Many methods have been created to test these attitudes. For example, Hess and Rueb created a 13-item scale and demonstrated its validity. However, this scale has several potential shortcomings. The developers did not report the reliability of the scale and its factor structure. Further, this scale includes a neutral point and legal language. One of the purposes of the present study was to develop a 12-item scale to address these issues. The present study compares and contrasts these two scales. Psychology student\u27s participated in this study. The results indicated that both abortion scales were reliable and valid. A factor analysis indicated that the Hess and Rueb scale has 3 factors, whereas the researchers newly developed scale had two factors. Implications of these findings are discussed

Reproduction and Growth of Black Drum, Pogonias cromis, in Northeast Florida

Age, growth, and reproduction of black drum, Pogonias cromis, in northeast Florida were investigated between December 1983 and April 1985. Male black drum began maturing at 450-499 mm total length (TL), with 50% of them reaching maturity at about 590 mm (age 4 or 5). Vitellogenesis began at 450-550 mm TL, with 50% of the females reaching maturity at 650-699 mm (age 5 or 6). Spawning occurred during January - April. Thin sections of otoliths displayed distinct opaque bands; the first three or four of these bands were verified by marginal increment analysis as being annuli deposited during March - May. The growth rate was about 100 mm yr-1 for ages 1·3 and gradually slowed to 10·30 mm yr-1 for ages 15-20. Male and female growth rates did not differ significantly, at least through age 4. Length at age was predicted well by the equation mm TL = 1172 mm (1 - exp (- 0.12 (AGE+ 1.3))). The apparent maximum age of black drum is about 50-60 years